Methods and apparatuses for reference signal transmission

ABSTRACT

Embodiments of the present disclosure relate to methods and devices for reference signal (RS) transmission. In example embodiments, a method implemented in a network device is provided. According to the method, a first set of RS resources are determined for RS transmission by the network device. The first set of RS resources are associated with a first number of RS ports to be used for RS transmission and correspond to a first set of resource elements (REs) interpolated with unused REs in frequency domain. A first RS configuration for RS transmission is generated based on the first set of RS resources. Information on the first RS configuration is transmitted to a terminal device served by the network device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.16/608,637 filed Oct. 25, 2019, which is a National Stage Entry ofPCT/CN2017/082186 filed Apr. 27, 2017.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field oftelecommunication, and in particular, to methods and apparatuses forreference signal (RS) transmission.

BACKGROUND

With the development of communication technologies, multiple types ofservices or traffic have been proposed, for example, enhanced mobilebroadband (eMBB) generally requiring high data rate, massive machinetype communication (mMTC) typically requiring long battery lifetime, andultra-reliable and low latency communication (URLLC). Meanwhile,multi-antenna schemes, such as beam management, reference signaltransmission, and so on, are studied for new radio access. Particularly,it has been agreed in 3GPP specification works that a Channel StateInformation-Reference Signal (CSI-RS) can support beam sweeping withinan Orthogonal Frequency Division Multiplexing (OFDM) symbol.

The CSI-RS should support the transmission (Tx) and reception (Rx) beamsweeping, which could help a terminal device to find out a good Tx-Rxbeam pair. To acquire the best Tx-Rx beam pair, given that there areN_(t) Tx beams and N_(r) Rx beams, the CSI-RS may need to provideN_(t)×N_(r) repetitions totally. If each repetition takes one symbol,totally N_(t)×N_(r) symbols may be needed for CSI-RS transmission. Thenumber of antennas at a specific Tx/Rx point (such as, a NodeB in newradio access) and the terminal device may be large, which means thenumber of beams to be swept would be large. In this case, some overheadand latency reduction schemes for CSI-RS transmission need to beconsidered.

SUMMARY

In general, example embodiments of the present disclosure providemethods and apparatuses for RS transmission.

In a first aspect, there is provided a method implemented in a networkdevice. According to the method, a first set of RS resources aredetermined for RS transmission by the network device. The first set ofRS resources are associated with a first number of RS ports to be usedfor RS transmission and correspond to a first set of resource elements(REs) interpolated with unused REs in frequency domain. A first RSconfiguration for RS transmission is generated based on the first set ofRS resources. Information on the first RS configuration is transmittedto a terminal device served by the network device.

In a second aspect, there is provided a method implemented in a terminaldevice. According to the method, information on a first RS configurationfor RS transmission by a network device is received from the networkdevice. The first RS configuration is determined based on a first set ofRS resources for RS transmission. The first set of RS resources areassociated with a first number of RS ports to be used for RStransmission and correspond to a first set of REs interpolated with atleast one unused RE in frequency domain. At least one RS sequence isdetected based on the first RS configuration.

In a third aspect, there is provided a network device. The networkdevice comprises a processor and a memory coupled to the processor. Thememory stores instructions that when executed by the processor, causethe network device to performs actions. The actions comprise:determining a first set of RS resources for RS transmission by thenetwork device, the first set of RS resources being associated with afirst number of RS ports to be used for RS transmission andcorresponding to a first set of REs interpolated with unused REs infrequency domain; generating, based on the first set of RS resources, afirst RS configuration for RS transmission; and transmitting to aterminal device served by the network device information on the first RSconfiguration.

In a fourth aspect, there is provided a terminal device. The terminaldevice comprises a processor and a memory coupled to the processor. Thememory stores instructions that when executed by the processor, causethe network device to performs actions. The actions comprise: receiving,from a network device, information on a first reference signal (RS)configuration for RS transmission by the network device, the first RSconfiguration being determined based on a first set of RS resources forRS transmission, the first set of RS resources being associated with afirst number of RS ports to be used for RS transmission andcorresponding to a first set of resource elements (REs) interpolatedwith at least one unused RE in frequency domain; and detecting, based onthe first RS configuration, at least one RS sequence.

Other features of the present disclosure will become easilycomprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the presentdisclosure in the accompanying drawings, the above and other objects,features and advantages of the present disclosure will become moreapparent, wherein:

FIG. 1 is a block diagram of a communication environment in whichembodiments of the present disclosure can be implemented;

FIG. 2 is a flowchart illustrating a process for RS transmissionaccording to some embodiments of the present disclosure;

FIG. 3 is a flowchart of an example method in accordance with someembodiments of the present disclosure;

FIG. 4A-4B shows examples of the selection of the first set of RSresources from the predefined set of RS resources according to someembodiments of the present disclosure;

FIG. 5 shows examples of the selection of the first set of RS resourcesfrom the predefined set of RS resources according to other embodimentsof the present disclosure;

FIG. 6 is a flowchart of an example method in accordance with someembodiments of the present disclosure;

FIGS. 7A-7D show examples of configuring the second set of RS resourcesaccording to some embodiments of the present disclosure;

FIG. 8A shows examples of the RPF indication in the RS configurationaccording to some embodiments of the present disclosure;

FIG. 8B shows examples of the information on the second RS configurationaccording to some embodiments of the present disclosure.

FIG. 9 is a flowchart of an example method in accordance with someembodiments of the present disclosure;

FIGS. 10A-10B show examples of resource mapping of different RSsequences according to some embodiments of the present disclosure;

FIGS. 11A-11B show examples of resource mapping of different RSsequences according to some embodiments of the present disclosure;

FIG. 12A-12B show examples of different power configurations for RStransmission according to some embodiments of the present disclosure;

FIG. 13 shows examples of SRS configurations associated with a CSI-RSconfiguration according to some embodiments of the present disclosure;

FIG. 14 is a block diagram of a network device in accordance with someembodiments of the present disclosure;

FIG. 15 is a block diagram of a terminal device in accordance with someembodiments of the present disclosure; and

FIG. 16 is a simplified block diagram of a device that is suitable forimplementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numeralsrepresent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with referenceto some example embodiments. It is to be understood that theseembodiments are described only for the purpose of illustration and helpthose skilled in the art to understand and implement the presentdisclosure, without suggesting any limitations as to the scope of thedisclosure. The disclosure described herein can be implemented invarious manners other than the ones described below.

In the following description and claims, unless defined otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skills in the art to which thisdisclosure belongs.

As used herein, the term “network device” or “base station” (BS) refersto a device which is capable of providing or hosting a cell or coveragewhere terminal devices can communicate. Examples of a network deviceinclude, but not limited to, a Node B (NodeB or NB), an Evolved NodeB(eNodeB or eNB), a next generation NodeB (gNB) a Remote Radio Unit(RRU), a radio head (RH), a remote radio head (RRH), a low power nodesuch as a femto node, a pico node, and the like. For the purpose ofdiscussion, in the following, some embodiments will be described withreference to gNB as examples of the network device.

As used herein, the term “terminal device” refers to any device havingwireless or wired communication capabilities. Examples of the terminaldevice include, but not limited to, user equipment (UE), personalcomputers, desktops, mobile phones, cellular phones, smart phones,personal digital assistants (PDAs), portable computers, image capturedevices such as digital cameras, gaming devices, music storage andplayback appliances, or Internet appliances enabling wireless or wiredInternet access and browsing and the like. For the purpose ofdiscussion, in the following, some embodiments will be described withreference to UE as examples of the terminal device.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The term “includes” and its variants are to be read as openterms that mean “includes, but is not limited to.” The term “based on”is to be read as “at least in part based on.” The term “one embodiment”and “an embodiment” are to be read as “at least one embodiment.” Theterm “another embodiment” is to be read as “at least one otherembodiment.” The terms “first,” “second,” and the like may refer todifferent or same objects. Other definitions, explicit and implicit, maybe included below.

In some examples, values, procedures, or apparatus are referred to as“best,” “lowest,” “highest,” “minimum,” “maximum,” or the like. It willbe appreciated that such descriptions are intended to indicate that aselection among many used functional alternatives can be made, and suchselections need not be better, smaller, higher, or otherwise preferableto other selections.

Communication discussed in the present disclosure may conform to anysuitable standards including, but not limited to, New Radio Access (NR),Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), WidebandCode Division Multiple Access (WCDMA), Code Division Multiple Access(CDMA) and Global System for Mobile Communications (GSM) and the like.Furthermore, the communications may be performed according to anygeneration communication protocols either currently known or to bedeveloped in the future. Examples of the communication protocolsinclude, but not limited to, the first generation (1G), the secondgeneration (2G), 2.5G, 2.75G, the third generation (3G), the fourthgeneration (4G), 4.5G, the fifth generation (5G) communicationprotocols.

FIG. 1 shows an example communication network 100 in which embodimentsof the present disclosure can be implemented. The network 100 includes anetwork device 110 and three terminal devices 120-1 and 120-3(collectively referred to as terminal devices 120 or individuallyreferred to as terminal device 120) served by the network device 110.The coverage of the network device 110 is also called as a cell 102. Itis to be understood that the number of base stations and terminaldevices is only for the purpose of illustration without suggesting anylimitations. The network 100 may include any suitable number of basestations and the terminal devices adapted for implementing embodimentsof the present disclosure. Although not shown, it would be appreciatedthat there may be one or more neighboring cells adjacent to the cell 102where one or more corresponding network devices provides service for anumber of terminal device located therein.

The network device 110 may communicate with the terminal devices 120.The communications in the network 100 may conform to any suitablestandards including, but not limited to, Long Term Evolution (LTE),LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division MultipleAccess (WCDMA), Code Division Multiple Access (CDMA) and Global Systemfor Mobile Communications (GSM) and the like. Furthermore, thecommunications may be performed according to any generationcommunication protocols either currently known or to be developed in thefuture. Examples of the communication protocols include, but not limitedto, the first generation (1G), the second generation (2G), 2.5G, 2.75G,the third generation (3G), the fourth generation (4G), 4.5G, the fifthgeneration (5G) communication protocols.

In addition to normal data communications, the network device 110 maysend a RS in a broadcast, multi-cast, and/or unicast manners to one ormore of the terminal devices 120 in a downlink. Similarly, one or moreof the terminal devices 120 may transmit RSs to the network device 110in an uplink. As used herein, a “downlink” refers to a link from anetwork device to a terminal device, while an “uplink” refers to a linkfrom the terminal device to the network device. For the purpose ofdiscussion without suggesting any limitations, in the followingdescription, some embodiments will be described with reference to thedownlink RS transmission.

For example, in the case of downlink RS transmission, the RS may be usedby the terminal devices 120 for beam sweeping, channel estimation,demodulation, and other operations for communication. Generallyspeaking, a RS is a signal sequence (also referred to as “RS sequence”)that is known by both the network device 110 and the terminal devices120. For example, a RS sequence may be generated and transmitted by thenetwork device 110 based on a certain rule and the terminal device 120may deduce the RS sequence based on the same rule. Examples of the RSmay include but are not limited to downlink or uplink DemodulationReference Signal (DMRS), Channel State Information-Reference Signal(CSI-RS), Sounding Reference Signal (SRS), Phase Tracking ReferenceSignal (PTRS) and so on. For the purpose of discussion withoutsuggesting any limitations, in the following description, someembodiments will be described with reference to CSI-RS as examples ofthe RS.

In transmission of downlink and uplink RSs, the network device 110 mayassign corresponding resources (also referred to as “RS resources”) forthe transmission and/or specify which RS sequence is to be transmitted.In some scenarios, both the network device 110 and the terminal device120 are equipped with multiple antenna ports (or antenna elements) andcan transmit specified RS sequences with the antenna ports (antennaelements). A set of RS resources associated with a number of RS portsare also specified. A RS port may be referred to as a specific mappingof part or all of a RS sequence to one or more resource elements of aresource region allocated for RS transmission in time, frequency, and/orcode domains.

As described above, a CSI-RS should support the Tx and Rx beam sweepingwithin an OFDM symbol to enable the terminal device to find out the bestTx-Rx beam pair. To acquire the best Tx-Rx beam pair, given that thereare N_(t) Tx beams and N_(r) Rx beams, the CSI-RS may need to provideN_(t)×N_(r) repetitions totally. If each repetition takes one symbol,totally N_(t)×N_(r) symbols may be needed for CSI-RS transmission. Withthe increasing of the number of antennas at the network device and theterminal device, the number of beams to be swept would become large.This may result in significant overhead and latency for the CSI-RStransmission.

In order to solve the problems above and one or more of other potentialproblems, a solution for RS transmission is provided in accordance withexample embodiments of the present disclosure. With the solution, anested structure of RS resources based on Interleaved Frequency DivisionMultiple Access (IFDMA) techniques can be provided. This nestedstructure of RS resources can support multiple repeated signals withinone symbol in time domain, such that the terminal device can detectmultiple beams within one symbol. Moreover, with the solution, multipleRS sequences can be mapped to different or same RS resources, such thatthe terminal device can detect the multiple RS sequences at the sametime. Therefore, the solution in accordance with embodiments of thepresent disclosure can greatly reduce the overhead and latency for RStransmission.

Principle and implementations of the present disclosure will bedescribed in detail below with reference to FIGS. 2-14 , in which FIG. 2shows a general process 200 for RS transmission according to someembodiments of the present disclosure. For the purpose of discussion,the process 200 will be described with reference to FIG. 1 . The process200 may involve the network device 110 and one or more terminal devices120 served by the network device 110.

The network device 110 may configure (210) some information for RStransmission. The information configured by the network device 110 mayinclude configuration of at least one of the following: a number of RSports, RS resources, a transmission pattern, a density, at least one RSsequence, a repetition factor, transmission power, and etc. The networkdevice may (220) indicate the information to the terminal device 120 bytransmitting a RS configuration. The terminal device 120 may receive(230), from the network device 110, the information configured for RStransmission. The network device 110 may transmit (240) the RS to theterminal device 120 based on the RS configuration. The terminal device120 may receive (250) the transmitted RS based on the RS configuration.

FIG. 3 shows a flowchart of an example method 300 in accordance withsome embodiments of the present disclosure. For the purpose ofdiscussion, the method 300 will be described with reference to FIG. 1 .The method 300 may involve the network device 110 and one or moreterminal devices 120 served by the network device 110.

In act 310, the network device 110 determines a first set of RSresources for RS transmission by the network device 110. The first setof RS resources may be associated with a first number of RS ports to beused for RS transmission and correspond to a first set of REs infrequency domain. In some embodiments, the first set of RS resources maybe selected from a predefined set of RS resources associated with apredetermined number of RS ports. In one embodiment, the first set of RSresources may be configured with the first number of RS ports and arepetition factor.

In one embodiment, the first number may be less than or equal to thepredetermined number of RS ports. The predetermined number (representedby N) may be same as the maximum number of RS ports being supported. Forexample, if the maximum number of RS ports is represented by M, thefirst number may be configured to be an integer which is not greaterthan M, such as 1, 2 . . . M. In other embodiments, the predeterminednumber N may be less than the maximum number of RS ports beingsupported, for example, N<M Then, the first number of RS portsassociated with the first set of RS resources may be configured to be aninteger which is not greater than N, such as 1, 2 . . . N.

In one embodiment, the maximum number of RS ports may be configured tobe 8. Then, the first number may be configured to be any of 1, 2, 4 and8. In other embodiments, the predetermined number may be less than themaximum number of RS ports being supported, for example, 4. Then, thefirst number of RS ports associated with the first set of RS resourcesmay be configured to be any of 1, 2 and 4.

In one embodiment, the repetition factor may be configured based on thecapability of the terminal device 120 (for example, whether multiplebeams can be detected within one symbol by the terminal device 120). Therepetition factor (RPF) may indicate a density of RS resources infrequency domain. For example, if the RPF equals to K (K>1), it mayindicate that K−1 unused REs are interpolated between every two adjacentREs for RS transmission. As known to those skilled in the art, K−1unused REs interpolated between every two adjacent REs may result in Krepeated signals within one symbol in time domain.

In one embodiment, the network device 110 may select, from a predefinedset of RS resources associated with the predetermined number of RSports, the first set of RS resources based on the first number of RSports and the repetition factor. That is, a subset of the predefined setof RS resources can be configured to be the first set of RS resources.

In one embodiment, For example, FIG. 4A shows some examples of theselection of the first set of RS resources from the predefined set of RSresources. FIG. 4A shows different sets of RS resources associated withdifferent RS ports in the case where the RPF equals to K. In FIG. 4A,each element may represent a RE in frequency domain. An occupied element(that is, an element which is filled with shadow) may represent a RE forRS transmission, while an unoccupied element (that is, an element whichis blank or filled with a cross) may represent an unused RE.

As shown in FIG. 4A, for example, the predefined set of RS resources isconfigured with a RPF value of K (also referred as “RPF-K”, where K isan integer and K>1). (K−1) unused REs are located between every twoadjacent REs for RS transmission. In one embodiment, if the first numberof RS ports is Q, a resource set for Q RS ports (also referred to as “aQ-port RS resource” for short) may be selected as the first set of RSresources. In another embodiment, if a Q-port RS resource has beendetermined, a P-port RS resource (where P is an integer and 1≤P<Q) maybe selected from the Q-port RS resource. For example, Q is a multiple ofP. In another embodiment, the P-port RS resource may be a subset of theQ-port RS resource, and the unselected resources may be unused for the PRS ports.

In another embodiment, for example, FIG. 4B shows some examples of theselection of the first set of RS resources from the predefined set of RSresources. FIG. 4B shows different sets of RS resources associated withdifferent RS ports in the case where the RPF equals to 2. In FIG. 4B,each element may represent a RE in frequency domain. An occupied element(that is, an element which is filled with shadow or indexed by anuppercase letter) may represent a RE for RS transmission, while anunoccupied element (that is, an element which is blank or filled with across) may represent an unused RE. Specifically, the uppercase lettersA-H each may represent an index of a RS port associated with the RE forRS transmission.

As shown in FIG. 4B, for example, the predefined set of RS resources maybe represented by a resource set 410 with a RPF value of 2. As shown bythe resource set 410, one unused RE is located between every twoadjacent REs for RS transmission. If the first number of RS ports isconfigured to be 8, an 8-port RS resource 411 may be selected as thefirst set of RS resources. Likewise, if an 8-port RS resource has beendetermined, a 4-port RS resource may be selected from the 8-port RSresource, such as a subset of the 8-port RS resource. Examples of the4-port RS resource are shown as 412-414, which are subsets of the 8-portRS resource 411. If an 8-port and/or 4-port RS resource has beendetermined, a 2-port RS resource may be selected from the 8-port and/or4-port RS resource, such as a subset of the 8-port and/or 4-port RSresource. Examples of the 2-port RS resource are shown as 415-419, eachof which is a subset of the 8-port RS resource 411 or any of the 4-portRS resources 412-414. If a 8-port RS resource, a 4-port RS resourceand/or a 2-port RS resource has been determined, a 1-port RS resourcemay be selected from any of the 8-port RS resource, the 4-port RSresource and/or the 2-port RS resource. For example, the 1-port RSresource may be a subset of any of the 8-port RS resource, the 4-port RSresource and/or the 2-port RS resource. Examples of the 1-port RSresource are shown as 420-427, each of which is a subset of any of the8-port RS resource 411, the 4-port RS resources 412-414 and the 2-portRS resources 415-419. In this way, a nested structure of RS resourcesbased on IFDMA techniques can be provided.

Similarly, FIG. 5 shows some examples of the selection of the first setof RS resources from the predefined set of RS resources according toanother embodiment of the present disclosure. FIG. 5 shows differentsets of RS resources associated with different RS ports in the casewhere the repetition factor equals to 4. In FIG. 5 , each element mayrepresent a RE in frequency domain. An occupied element (that is, anelement which is filled with shadow or indexed by an uppercase letter)may represent a RE for RS transmission, while an unoccupied element(that is, an element which is blank or filled with a cross) mayrepresent an unused RE. Specifically, the uppercase letters A-H each mayrepresent an index of a RS port associated with the RE for RStransmission.

As shown in FIG. 5 , for example, the predefined set of RS resources maybe represented by a resource set 510 with a RPF value of 4. As shown bythe resource set 510, three unused REs are located between every twoadjacent REs for RS transmission. If the first number of RS ports isconfigured to be 8, an 8-port resource 511 may be selected as the firstset of RS resources. Likewise, if an 8-port RS resource has beendetermined, a 4-port RS resource may be selected from the 8-port RSresource, such as a subset of the 8-port RS resource. Examples of the4-port RS resource are shown as 512-513, which are subsets of the 8-portRS resource 511. If an 8-port and/or 4-port RS resource has beendetermined, a 2-port RS resource may be selected from the 8-port and/or4-port RS resource, such as a subset of the 8-port and/or 4-port RSresource. Examples of the 2-port RS resource are shown as 514-517, eachof which is a subset of the 8-port RS resource 511 or any of the 4-portRS resources 512-513. If a 8-port RS resource, a 4-port RS resourceand/or a 2-port RS resource has been determined, a 1-port RS resourcemay be selected from any of the 8-port RS resource, the 4-port RSresource and/or the 2-port RS resource. For example, the 1-port RSresource may be a subset of any of the 8-port RS resource, the 4-port RSresource and/or the 2-port RS resource. Examples of the 1-port RSresource are shown as 518-525, each of which is a subset of any of the8-port RS resource 511, the 4-port RS resources 512-513 and the 2-portRS resources 514-517.

In one embodiment, the RS ports with different indices may be associatedwith beams. For example one beam associated with one RS port with anindex A may be different from another beam associated with another RSport with an index B. In another embodiment, the RS ports may not bemultiplexed with orthogonal cover code (OCC).

Referring back to FIG. 3 , the method 300 exceeds to act 320, where theterminal device 110 generates, based on the first set of RS resources, aRS configuration (also referred to as “first RS configuration” in thefollowing description) for RS transmission. As used herein, a RSconfiguration is used to specify one or more aspects of transmission ofa RS, for example, a set of RS resources to be used for thetransmission, and/or at least one RS sequence to be transmitted. In someembodiments, the first RS configuration may specify the first set of RSresources to be used for RS transmission.

In act 330, the network device 110 transmits to the terminal device 120information on the first RS configuration. The information may indicateto the terminal device 120 one or more aspects of the RS transmission asspecified in the first RS configuration. For example, depending on thefirst RS configuration, the information may indicate to the terminaldevice 120 that the first set of RS resources are to be used in the RStransmission.

In act 340, the terminal device 120 receives, from the network device110, the information on the first RS configuration. The terminal device120 may determine from the first RS configuration how the RStransmission would be performed. For example, the terminal device 120may be configured with the first set of RS resources to be used for RStransmission. The terminal device 120 may be configured with the firstset of RS resources, which correspond to the first set of REsinterpolated with unused REs in frequency domain.

In one embodiment, in addition to the set of RS resources (for example,the first set of RS resources) to be used for RS transmission, thenetwork device 110 may also configure at least one RS sequence to theterminal device 120. The network device 110 may transmit to the terminaldevice 120 the at least one RS sequence based on the configuration. Forexample, the network device 110 may transmit the at least one sequencewith the configured set of RS resources. Then, at the receiving side,the terminal device 120 may detect the at least one sequence based onthe RS configuration.

In some embodiments, a plurality of RS configurations may be configuredfor different purposes. The plurality of RS configurations may beconfigured based on different RS resources and/or different RSsequences. For example, different RS resources can be used fortransmission of different RSs from different TRPs, different beamsand/or different antenna panels.

To configure different RS resources for RS transmission, FIG. 6 shows anexample method 600 for RS transmission according to some embodiments ofthe present disclosure. For the purpose of discussion, the method 600will be described with reference to FIG. 1 . The method 600 may involvethe network device 110 and one or more terminal devices 120 served bythe network device 110. It should be understood that the method 600 mayalso comprise additional acts (not shown) and/or may omit theillustrated acts. The scope of the present disclosure described hereinis not limited in this aspect.

In act 610, the network device 110 determines, from the predefined setof RS resources and at least in part based on the first RSconfiguration, a second set of RS resources for RS transmission. Thesecond set of RS resources may correspond to a second set of REs infrequency domain.

In some embodiments, the network device 110 may configure the second setof RS resources, such that the second set of RS resources are associatedwith the same number of RS ports and the same repetition factor as thefirst set of RS resources. That is, the network device 110 can configurea different subset of the predefined set of RS resources to be thesecond set of RS resources. Referring back to FIG. 4B, for example, ifthe first number of RS ports is 4 and the first set of RS resources areconfigured to be the 4-port RS resource 412, the 4-port RS resource 413or 414 may be configured as the second set of RS resources. In someembodiment, the first and second set of RS resources can be separatefrom one another in frequency domain (as shown by the 4-port RSresources 412 and 413). Alternatively, in other embodiments, the firstset of RS resources may be at least partially overlapped with the secondset of RS resources (as shown by the 4-port RS resources 412 and 414).Similarly, if the first number of RS ports is 2 and the first set of RSresources are configured to be the 2-port RS resource 415, any of the2-port RS resources 416-419 may be configured as the second set of RSresources.

In some embodiments, the network device may configure the second set ofRS resources based on a shift value in frequency and/or time domain. Forexample, the network device 110 may configure the second set of RSresources by shifting at least part of the first set of REs with theshift value. In one embodiment, as shown in FIG. 4B, if the first set ofRS resources is configured to be a 4-port RS resource 412, the secondset of RS resources may be configured by shifting at least part of the4-port RS resource 412, and examples of the second set of RS resourcesmay be shown as 413-414. Alternatively, if the first set of RS resourcesis configured to be a 2-port RS resource 415, the second set of RSresources may be configured by shifting at least part of the 2-port RSresource 415, and examples of the second set of RS resources may beshown as 416-419. Alternatively, if the first set of RS resources isconfigured to be a 1-port RS resource 420, the second set of RSresources may be configured by shifting at least part of the 1-port RSresource 420, and examples of the second set of RS resources may beshown as 421-427.

In another embodiment, FIG. 7A and FIG. 7D show examples of configuringthe second set of RS resources according to some embodiments of thepresent disclosure. As shown in FIG. 7D, if the first set of RSresources is configured to be a 4-port RS resource 740, the second setof RS resources may be configured by shifting at least part of the4-port RS resource 740, and one example of the second set of RSresources may be shown as 710 in FIG. 7A. Alternatively, if the firstset of RS resources is configured to be a 2-port RS resource 741 asshown in FIG. 7D, the second set of RS resources may be configured byshifting at least part of the 2-port RS resource 741, and examples ofthe second set of RS resources may be shown as 721-723 in FIG. 7A.Alternatively, if the first set of RS resources is configured to be a1-port RS resource 742 as shown in FIG. 7D, the second set of RSresources may be configured by shifting at least part of the 1-port RSresource 742, and examples of the second set of RS resources may beshown as 724-730 in FIG. 7A.

In some embodiments, the network device may configure the second set ofRS resources, such that the second set of RS resources are associatedwith the same number of RS ports as the first set of RS resources whilehave a higher density than the first set of RS resources. For example,the second set of RS resources may be associated with a smallerrepetition factor than the first set of RS resources. In one embodiment,FIG. 7B and FIG. 7D show examples of configuring the second set of RSresources according to some embodiments of the present disclosure. Asshown in FIG. 7B, if the first set of RS resources is configured to bethe 4-port RS resource 710 or 740, a 4-port RS resource 731 or 732 maybe configured to be the second set of RS resources. If the first set ofRS resources is configured to be a 2-port RS resource 741 or 722, a2-port RS resource 734 may be configured to be the second set of RSresources. Alternatively, if the first set of RS resources is configuredto be a 2-port RS resource 721 or 723, a 2-port RS resource 733 or 735may be configured to be the second set of RS resources. Similarly, theexamples about a 1-port RS resource are shown by 1-port RS resources 736and 737.

In some embodiments, the network device may configure the second set ofRS resources, such that the second set of RS resources are associatedwith a different number of RS ports from the first set of RS resourcesbut the same repetition factor as it. For example, the second set of RSresources may be associated with a second number of RS ports, where thesecond number is greater than the first number. In another example, thesecond number is a multiple of the first number. In this case, thesecond set of REs corresponding to the second set of RS resources infrequency domain may include the first set of REs corresponding to thefirst set of REs with same indexing. In this regard, FIG. 7C showsexamples of configuring the second set of RS resources according to someembodiments of the present disclosure. As shown in FIG. 7C, if the firstset of RS resources is configured to be a 4-port RS resource 740, thesecond set of RS resources may be configured to be an 8-port RS resource738.

In some embodiments, the network device may configure the second set ofRS resources, such that the second set of RS resources are associatedwith a different number of RS ports from the first set of RS resources,and the second set of REs are include in the first set of REs with sameindexing.

In one embodiment, FIG. 7D shows examples of configuring the second setof RS resources according to some embodiments of the present disclosure.As shown in FIG. 7D, if the first set of RS resources is configured tobe an 8-port RS resource (for example, the 8-port RS resource 739) andthe second number of RS ports is 4, the second set of RS resources maybe configured for 4 RS ports. The second set of RS resources may beincluded in the 8-port RS resource, and the indexing for the 4 RS portsin the 4-port resource (that is, the second set of RS resources) may besame as that for the 4 RS ports in the 8-port RS resource. An example ofthe second set of RS resources for 4 RS ports is shown as 740.Alternatively, if the second number of RS ports is 2, the second set ofRS resources may be configured for 2 RS ports, and the second set of RSresources may be included in a 8-port and/or 4-port resource, and theindexing for the 2 RS ports may be same as that for the 2 ports in the8-port resource 739 and/or the 4-port resource 740. An example of thesecond set of RS resources for 2 RS ports is shown as 741.Alternatively, if the second number of RS ports is 1, the second set ofRS resources may be configured for 1 RS port. The second set of RSresources may be included in a 8-port RS resource, a 4-port RS resourceand/or a 2-port RS resource, and the indexing for the 1 RS port may besame as the 1 port in the 8-port RS resource 739, the 4-port RS resource740 and/or the 2-port resource 741. An example of the second set of RSresources for 1 RS port is shown as 742. It can be seen that the 4-portRS resource 740 is included in the 8-port RS resource 739 with sameindexing for the 4 RS ports. The 2-port RS resource 741 is included inthe 8-port RS resource 739 and/or the 4-port RS resource 740 with sameindexing for the 2 RS ports. The 1-port RS resource 742 is included inthe 8-port resource 739, the 4-port resource 740, and/or the 2-portresource 741 with same indexing for the 1 RS port.

Referring back to FIG. 6 , the method 600 exceeds to act 620, where theterminal device 110 generates, based on the second set of RS resources,a RS configuration (also referred to as “second RS configuration” in thefollowing description) for RS transmission. The second RS configurationmay specify the second set of RS resources to be used for RStransmission.

In act 630, the network device 110 transmits to the terminal device 120information on the second RS configuration. The information may indicateto the terminal device 120 one or more aspects of the RS transmission asspecified in the second RS configuration. For example, depending on theconfigured second RS configuration, the information may indicate to theterminal device 120 that the second set of RS resources are to be usedin the RS transmission.

In some embodiments, the information on the RS configuration may includean indication of a corresponding RPF. FIG. 8A shows examples of the RPFindication in the RS configuration according to some embodiments of thepresent disclosure. For example, the network device may configure a setof RPF values for one RS configuration, as shown in FIG. 8A. The RSconfiguration may also include configuration of at least one of thefollowing: time and/or frequency resources, a transmission pattern, anumber of RS ports, at least one RS sequence, and etc. In anotherembodiment, the RPF configuration for different RS configurations may bedifferent. In another embodiment, for some RS configurations, only oneRPF value may be supported, and thus for the RS configuration, theindication of the corresponding RPF may not be needed.

In another embodiment, the information on the RS configuration mayinclude an indication of a corresponding RPF value. For example, thenetwork device may have already configured the first set of RS resourcesfor RS transmission via the first RS configuration. In this case, thenetwork device may further configure the second set of RS resources forRS transmission by indicating a different RPF to be applied to the firstset of RS resources. For example, the information on the second RSconfiguration may include an optional field to indicate thecorresponding RPF. In this regard, FIG. 8B shows examples of theinformation on the second RS configuration according to some embodimentsof the present disclosure. As shown in FIG. 8B, if the firstconfiguration corresponds to a 4-port RS resource 810 (that is the firstset of RS resources) which has already been configured to the terminaldevice 120, the network device 110 may indicate to the terminal device120 a RPF value of 2 or 4 in the information on the secondconfiguration. That is, the 4-port RS resource 810 can support differentRPF values for different RS configurations. However, the other three RSconfigurations 820-840 only support one RPF value which is 2. In thiscase, information on the other three RS configurations 820-840 may haveno field for indicating the RPF value.

Referring back to FIG. 6 , the method 600 exceeds to act 640, where theterminal device 120 receives, from the network device 110, theinformation on the second RS configuration. The terminal device 120 maydetermine from the second RS configuration how the RS transmission wouldbe performed. For example, the terminal device 120 may be configuredwith the second set of RS resources to be used for RS transmission. Theterminal device 120 may be configured with the second set of RSresources, which correspond to the second set of REs interpolated withunused REs in frequency domain.

In act 650, the network device 110 may transmit to the terminal device120 at least one RS sequence based on the second configuration. Forexample, the network device 110 may transmit the at least one sequencewith the configured second set of RS resources. Then, at the receivingside of the RS transmission, in act 660, the terminal device 120 maydetect the at least sequence based on the second RS configuration.

To support detection of different RS sequences at the same time, FIG. 9shows a process 900 for RS transmission according to some embodiments ofthe present disclosure. For the purpose of discussion, the process 900will be described with reference to FIG. 1 . The process 900 may involvethe network device 110 and one or more terminal devices 120 served bythe network device 110. It should be understood that the process 900 mayalso comprise additional acts (not shown) and/or may omit theillustrated acts. The scope of the present disclosure described hereinis not limited in this aspect.

In act 910, the network device 110 generates a third RS configurationabout at least one RS sequence to be transmitted to the terminal device120. In some embodiments, examples of the RS sequences may include butnot limited to pseudorandom noise (PN) sequences, Zadoff-Chu (ZC)sequences, or the like.

In some embodiments, the third RS configuration about the at least oneRS sequence may be dependent from the first or second RS configuration.In other embodiments, the third RS configuration can be included in thefirst or second RS configuration. That is, the first or second RSconfiguration may include configurations about both RS resources and RSsequences.

In some embodiments, the third RS configuration may indicate the numberof RS sequences in the at least one RS sequence to be transmitted.Alternatively, the third RS configuration may also indicate which RSresources are to be used for transmitting different RS sequences.

In some embodiments, the third RS configuration may indicate that thedifferent RS sequences are to be transmitted with same RS resources. Inother embodiments, for example, the third RS configuration may indicatethat the different RS sequences are to be transmitted with different RSresources. FIGS. 10A-10B show examples of resource mapping of differentRS sequences according to some embodiments of the present disclosure. InFIG. 10A, different RS sequences 1010 are mapped to same RS resources.In FIG. 10B, the different RS sequences 1010 are mapped to different RSresources.

In some embodiments, for example, the at least one RS sequence mayinclude at least first and second RS sequences. The third RSconfiguration may indicate that the first RS sequence is to betransmitted with the first set of RS resources, while the second RSsequence is to be transmitted with the second set of RS resources. FIGS.11A-11B show examples of resource mapping of different RS sequencesaccording to some embodiments of the present disclosure. In FIG. 11A, RSsequences 1110 and 1120 are mapped to a 4-port RS resource 1130. In FIG.11B, the RS sequence 1110 is mapped to the 4-port RS resource 1140,while the RS sequence 1120 is mapped to another 4-port RS resource 1150.

Referring back to FIG. 9 , the process 900 exceeds to act 920, where thenetwork device 110 transmits to the terminal device 120 information onthe third RS configuration.

In some embodiments, the information on the third RS configuration maybe transmitted via high level signaling and/or dynamic signaling.Examples of the high level signaling may include but not limited tosignaling on Radio Resource Control (RRC) Layer, or Media Access Control(MAC) layer. Examples of the dynamic signaling may include but notlimited to Downlink Control Information (DCI).

In some embodiments, the network device 110 may perform a multi-levelconfiguration for a plurality of RS sequences. For example, the networkdevice 110 may be configured with L (L≥1) RS sequences for the terminaldevices 120 via the higher layer signaling. The network device 110 maythen configure G (1≤G≤L) RS sequences out of the L RS sequences for someof the terminal devices 120 via the higher layer signaling or thedynamic signaling.

In act 930, the terminal device 120 receives, from the network device110, the third RS configuration about the at least one RS sequence. Theterminal device 120 may be configured with the number of RS sequences tobe transmitted. The terminal device 120 may also be configured withwhich RS resources to be used for transmitting different RS sequences.In some embodiments, the terminal device 120 may be configured withinformation that the different RS sequences are to be transmitted withsame RS resources. In other embodiments, the terminal device 120 may beconfigured with information that the different RS sequences are to betransmitted with different RS resources. Specifically, in someembodiments, the at least one RS sequence may include at least first andsecond RS sequences. The terminal device 120 may be configured withinformation that the first RS sequence is to be transmitted with thefirst set of RS resources, while the second RS sequence is to betransmitted with the second set of RS resources.

In act 940, the network device 110 may transmit to the terminal device120 at least one RS sequence based on the third configuration. Then, inact 950, the terminal device 120 may detect the at least one RS sequencebased on the third RS configuration.

The terminal device 120 may detect the at least one RS sequence with theRS resources indicated by the third RS configuration. For example, insome embodiment, the third RS configuration may indicate that the atleast one RS sequence is transmitted with the first set of RS resources.In this case, the terminal device 120 may detect the at least one RSsequence with the first set of RS resources. In other embodiments, theat least one RS sequence may include at least first and second RSsequences. The third configuration may indicate that the first RSsequence is to be transmitted with the first set of RS resources, whilethe second RS sequence is to be transmitted with the second set of RSresources. In this case, the terminal device 120 may detect the first RSsequence with the first set of RS resources and detect the second RSsequence with the third set of RS resources.

In view of the above, the proposed solution for RS transmission canprovide a nested structure of RS resources based on IFDMA techniques.This nested structure of RS resources can support multiple repeatedsignals within one symbol in time domain, such that the terminal devicecan detect multiple beams within one symbol. Moreover, with thesolution, multiple RS sequences can be mapped to different or same RSresources, such that the terminal device can detect the multiple RSsequences at the same time. Therefore, the solution in accordance withembodiments of the present disclosure can greatly reduce the overheadand latency for RS transmission.

In addition, the proposed solution may provide considerations about someother aspects of RS transmission.

For example, in some embodiments, the RS resources for beam managementmay not be used for interference measurement. For example, some RSconfigurations may be configured for beam management. The RSconfigurations may indicate some resources for RS transmission, and theresources indicated by the RS configurations may not be configured asthe resources for interference measurement.

In some embodiments, the RS resources for beam management may beconfigured with partial band. For frequencies out of the partial band,other signals (such as Physical Downlink Shared Channel, PhysicalDownlink Control Channel, Synchronization Signal Block, and etc.) ratherthan the RS can be transmitted. For the transmission of other signals, asame RPF value as the RS transmission can be applied.

In some embodiments, whether multiple beams can be detected within onesymbol may depend on the capability of the terminal device. For example,in one embodiment, the terminal device may have different capabilitiesto detect the RS. The terminal device may report information on thecapability to the network device. In other embodiment, the networkdevice may receive the information on the capability, and the networkdevice may configure the RS with a RPF value K based on the informationon the capability. In another embodiment, the terminal device may havedifferent capabilities to detect the RS, and the reported informationmay be different based on the different capabilities. For example, inone embodiment, the terminal device may have different capabilities todetect the RS, and the terminal device can detect multiple beams withinone symbol. In this case, the terminal device may select one or morebeams within one symbol and report the selection to the network device.

In some embodiments, power boosting may be applied to the set of RSresources allocated for RS transmission. The power of RS transmissionfor beam management can be different from power of other RStransmissions, for example, RS transmission for CSI acquisition. In someembodiments, the power of RS transmission may have different powervalues, which may be based on the RPF value and/or the number of RSports. In one embodiment, for different RPF configurations, values ofthe power may be different, for example as shown in FIG. 12A. In anotherembodiment, for different number of RS ports, values of the power may bedifferent, for example as shown in FIG. 12B.

In one embodiment, the network device may configure different powerparameters to the terminal device, and the different power parametersmay be associated with different RPF values and/or different number ofRS ports. In another embodiment, the network device may configureinformation on a reference power to the terminal device. The network mayalso configure different power offset values relative to the referencepower for RS transmissions with different PRF values and/or differentnumber of RS ports. For example, the information on the reference powermay be used to indicate the power of RS transmission for reference. Foranother example, the information on the reference power may be used forRS transmission with a fixed RPF value K and/or a fixed number of RSports H.

In some embodiments, a configuration of SRS transmission may beassociated with the RS configuration. For example, at least part of SRSconfigurations may be mapped to at least part of CSI-RS configurations,and the SRS configurations may include information on at least one ofthe following: SRS resources, SRS sequences, SRS transmission bands andetc. In addition, the CSI-RS configurations may indicate at least one ofCSI-RS resources, CSI-RS port indices and etc. In one embodiment, forexample, at least part of SRS resources and/or SRS sequences are mappedto at least part of CSI-RS resources, such as one or more of CSI-RSports. For example as shown in FIG. 13 , different SRS configurationsmay be associated with different CSI-RS ports. For example, each of theCSI-RS ports may correspond to one beam. For example, once the terminaldevice selects one beam, the terminal device can transmit a SRS with anassociated CSI-RS port.

FIG. 14 shows a block diagram of an apparatus 1400 in accordance withsome embodiments of the present disclosure. The apparatus 1400 can beconsidered as an example implementation of the network device 110 asshown in FIG. 1 . As shown, the apparatus 1400 includes a determiningmodule 1410 configured to determine a first set of reference signal (RS)resources for RS transmission by the network device, the first set of RSresources being associated with a first number of RS ports to be usedfor RS transmission and corresponding to a first set of resourceelements (REs) interpolated with unused REs in frequency domain. Theapparatus 1400 also includes a generating module 1420 configured togenerate, based on the first set of RS resources, a first RSconfiguration for RS transmission. In addition, the apparatus 1400 mayalso include a transmitting module 1430 configured to transmit to aterminal device served by the network device information on the first RSconfiguration.

FIG. 15 shows a block diagram of an apparatus 1500 in accordance withsome embodiments of the present disclosure. The apparatus 1500 can beconsidered as an example implementation of the terminal device 120 asshown in FIG. 1 . As shown, the apparatus 1500 includes a receivingmodule 1510 configured to receive, from a network device, information ona first reference signal (RS) configuration for RS transmission by thenetwork device, the first RS configuration being determined based on afirst set of RS resources for RS transmission, the first set of RSresources being associated with a first number of RS ports to be usedfor RS transmission and corresponding to a first set of resourceelements (REs) interpolated with at least one unused RE in frequencydomain. The apparatus 1500 also includes a detecting module 1520configured to detect, based on the first RS configuration, at least oneRS sequence.

For the sake of clarity, FIGS. 14 and/or 15 do not illustrate someoptional modules of the apparatuses 1400 and/or 1500. However, it shouldbe understood that various features as described with reference to FIGS.1-13 are likewise applicable to the apparatuses 1400 and/or 1500.Moreover, respective modules of the apparatuses 1400 and/or 1500 may behardware modules or software modules. For example, in some embodiments,the apparatuses 1400 and/or 1500 may be implemented partially orcompletely by software and/or firmware, e.g., implemented as a computerprogram product embodied on the computer-readable medium. Alternatively,or in addition, the apparatuses 1400 and/or 1500 may be partially orcompletely implemented based on hardware, e.g., implemented as anintegrated circuit (IC), an application-specific integrated circuit(ASIC), a system on chip (SOC), a field programmable gate array (FPGA)and the like. The scope of the present disclosure is not limited in thisaspect.

FIG. 16 is a simplified block diagram of a device 1600 that is suitablefor implementing embodiments of the present disclosure. The device 1600can be considered as a further example implementation of a networkdevice 110 or a terminal device 120 as shown in FIG. 1 . Accordingly,the device 1600 can be implemented at or as at least a part of thenetwork device 110 or the terminal device 120.

As shown, the device 1600 includes a processor 1610, a memory 1620coupled to the processor 1610, a suitable transmitter (TX) and receiver(RX) 1640 coupled to the processor 1610, and a communication interfacecoupled to the TX/RX 1640. The memory 1610 stores at least a part of aprogram 1630. The TX/RX 1640 is for bidirectional communications. TheTX/RX 1640 has at least one antenna to facilitate communication, thoughin practice an Access Node mentioned in this application may haveseveral ones. The communication interface may represent any interfacethat is necessary for communication with other network elements, such asX2 interface for bidirectional communications between eNBs, S1 interfacefor communication between a Mobility Management Entity (MME)/ServingGateway (S-GW) and the eNB, Un interface for communication between theeNB and a relay node (RN), or Uu interface for communication between theeNB and a terminal device.

The program 1630 is assumed to include program instructions that, whenexecuted by the associated processor 1610, enable the device 1600 tooperate in accordance with the embodiments of the present disclosure, asdiscussed herein with reference to FIGS. 1 to 13 .

The embodiments herein may be implemented by computer softwareexecutable by the processor 1610 of the device 1600, or by hardware, orby a combination of software and hardware. The processor 1610 may beconfigured to implement various embodiments of the present disclosure.Furthermore, a combination of the processor 1610 and memory 1610 mayform processing means 1650 adapted to implement various embodiments ofthe present disclosure.

The memory 1610 may be of any type suitable to the local technicalnetwork and may be implemented using any suitable data storagetechnology, such as a non-transitory computer readable storage medium,semiconductor based memory devices, magnetic memory devices and systems,optical memory devices and systems, fixed memory and removable memory,as non-limiting examples. While only one memory 1610 is shown in thedevice 1600, there may be several physically distinct memory modules inthe device 1600. The processor 1610 may be of any type suitable to thelocal technical network, and may include one or more of general purposecomputers, special purpose computers, microprocessors, digital signalprocessors (DSPs) and processors based on multicore processorarchitecture, as non-limiting examples. The device 1600 may havemultiple processors, such as an application specific integrated circuitchip that is slaved in time to a clock which synchronizes the mainprocessor.

Generally, various embodiments of the present disclosure may beimplemented in hardware or special purpose circuits, software, logic orany combination thereof. Some aspects may be implemented in hardware,while other aspects may be implemented in firmware or software which maybe executed by a controller, microprocessor or other computing device.While various aspects of embodiments of the present disclosure areillustrated and described as block diagrams, flowcharts, or using someother pictorial representation, it will be appreciated that the blocks,apparatus, systems, techniques or methods described herein may beimplemented in, as non-limiting examples, hardware, software, firmware,special purpose circuits or logic, general purpose hardware orcontroller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer programproduct tangibly stored on a non-transitory computer readable storagemedium. The computer program product includes computer-executableinstructions, such as those included in program modules, being executedin a device on a target real or virtual processor, to carry out theprocess or method as described above with reference to any of FIGS. 1 to13 . Generally, program modules include routines, programs, libraries,objects, classes, components, data structures, or the like that performparticular tasks or implement particular abstract data types. Thefunctionality of the program modules may be combined or split betweenprogram modules as desired in various embodiments. Machine-executableinstructions for program modules may be executed within a local ordistributed device. In a distributed device, program modules may belocated in both local and remote storage media.

Program code for carrying out methods of the present disclosure may bewritten in any combination of one or more programming languages. Theseprogram codes may be provided to a processor or controller of a generalpurpose computer, special purpose computer, or other programmable dataprocessing apparatus, such that the program codes, when executed by theprocessor or controller, cause the functions/operations specified in theflowcharts and/or block diagrams to be implemented. The program code mayexecute entirely on a machine, partly on the machine, as a stand-alonesoftware package, partly on the machine and partly on a remote machineor entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium,which may be any tangible medium that may contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device. The machine readable medium may be a machinereadable signal medium or a machine readable storage medium. A machinereadable medium may include but not limited to an electronic, magnetic,optical, electromagnetic, infrared, or semiconductor system, apparatus,or device, or any suitable combination of the foregoing. More specificexamples of the machine readable storage medium would include anelectrical connection having one or more wires, a portable computerdiskette, a hard disk, a random access memory (RAM), a read-only memory(ROM), an erasable programmable read-only memory (EPROM or Flashmemory), an optical fiber, a portable compact disc read-only memory(CD-ROM), an optical storage device, a magnetic storage device, or anysuitable combination of the foregoing.

Further, while operations are depicted in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results. Incertain circumstances, multitasking and parallel processing may beadvantageous. Likewise, while several specific implementation detailsare contained in the above discussions, these should not be construed aslimitations on the scope of the present disclosure, but rather asdescriptions of features that may be specific to particular embodiments.Certain features that are described in the context of separateembodiments may also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment may also be implemented in multipleembodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specificto structural features and/or methodological acts, it is to beunderstood that the present disclosure defined in the appended claims isnot necessarily limited to the specific features or acts describedabove. Rather, the specific features and acts described above aredisclosed as example forms of implementing the claims.

What is claimed is:
 1. A method performed by a User Equipment (UE), themethod comprising: receiving, from a base station, configurationinformation configuring a first resource for a Channel State InformationReference Signal (CSI-RS), wherein, the first resource comprises one ormore resource elements allocated for the CSI-RS, the first resource iswithin a first partial frequency band, and the first partial frequencyband is configured within a downlink frequency region where a PhysicalDownlink Shared Channel (PDSCH) is received; receiving, from the basestation, the CSI-RS on the first resource, wherein the CSI-RS is notreceived out of the first partial frequency band; and transmitting, tothe base station, a Sounding Reference Signal (SRS) on an SRS resourceassociated with the first resource, based on reception of the CSI-RS. 2.The method of claim 1, wherein second information related to a beam fortransmission of the SRS is determined by the UE.
 3. The method of claim1, wherein the SRS resource is a frequency domain resource configured byan SRS resource configuration.
 4. The method of claim 1, furthercomprising: selecting a configuration of the SRS based on a detectedbeam of the CSI-RS, by using the configuration information.
 5. Themethod of claim 1, wherein the configuration information indicates anumber of ports for the CSI-RS.
 6. The method of claim 1, wherein theconfiguration information indicates a density of the CSI-RS.
 7. A methodperformed by a base station, the method comprising: transmitting, to aUser Equipment (UE), configuration information configuring a firstresource for a CSI-RS (Channel State Information Reference Signal),wherein, the first resource comprises one or more resource elementsallocated for the CSI-RS, the first resource is within a first partialfrequency band, and the first partial frequency band is configuredwithin a downlink frequency region where a Physical Downlink SharedChannel (PDSCH) is transmitted; transmitting, to the UE, the CSI-RS onthe first resource, wherein the CSI-RS is not transmitted out of thefirst partial frequency band; receiving, from the UE, a SoundingReference Signal (SRS) on an SRS resource associated with the firstresource, based on transmission of the CSI-RS.
 8. The method of claim 7,wherein second information related to a beam for transmission of the SRSis determined by the UE.
 9. The method of claim 7, wherein the SRSresource is a frequency domain resource configured by an SRS resourceconfiguration.
 10. The method of claim 7, wherein, a configuration ofthe SRS based on a detected beam of the CSI-RS is selected by the UEusing the configuration information.
 11. The method of claim 7, whereinthe configuration information indicates a number of ports for theCSI-RS.
 12. The method of claim 7, wherein the configuration informationindicates a density of the CSI-RS.
 13. A network device comprising: aprocessor; and a memory coupled to the processor and storinginstructions thereon, the instructions, when executed by the processor,causing the network device to perform actions, the actions comprising:transmitting, to a User Equipment (UE), configuration informationconfiguring a first resource for a CSI-RS (Channel State InformationReference Signal), wherein, the first resource comprises one or moreresource elements allocated for the CSI-RS, the first resource is withina first partial frequency band, and the first partial frequency band isconfigured within a downlink frequency region where a Physical DownlinkShared Channel (PDSCH) is transmitted; transmitting, to the UE, theCSI-RS on the first resource, wherein the CSI-RS is not transmitted outof the first partial frequency band; and receiving, from the UE, aSounding Reference Signal (SRS) on an SRS resource associated with thefirst resource, based on transmission of the CSI-RS.
 14. The networkdevice of claim 13, wherein second information related to a beam fortransmission of the SRS is determined by the UE.
 15. The network deviceof claim 13, wherein the SRS resource is a frequency domain resourceconfigured by an SRS resource configuration.
 16. The network device ofclaim 13, wherein a configuration of the SRS based on a detected beam ofthe CSI-RS is selected by the UE using the configuration information.17. The network device of claim 13, wherein the configurationinformation indicates a number of ports for the CSI-RS.
 18. The networkdevice of claim 13, wherein the configuration information indicates adensity of the CSI-RS.